In shale gas wells, water is used to carry a propping agent, such as sand, under pressure, into a wellbore. The pressure causes the rock to ‘fracture’, and thereby release the trapped gas. These fractures are held open by the propping agent. The water for this purpose is stored in lined open top tanks and is extracted from the tank at high volumes, up to 18 m3/min. The open top tank should be leak proof, which is accomplished through the use of geomembrane liners. If the liner becomes damaged, the tank becomes at risk of developing a leak. The liner is typically either a one piece liner that is positioned inside the tank, covering the floor and the walls of the tank, or is several rolls of liner that are welded together to form a seal. The liner covers the floor and walls of the tank to form a watertight layer, independent of the tank structure.
Prior art pumping methods from lined open top tanks include:                a suction intake positioned at the bottom of the tank (usually at a bell hole), which is then piped under the wall of the tank and exits to the surface at the exterior of the tank wall. As a hole being cut in the liner; the intake extrusion is welded to the liner with a gasket;        a suction intake running through the wall of the tank, wherein a hole is cut in the liner and the tank wall, and the hole and piping are patch welded to create a seal;        a suction pipe that runs up over the wall of the tank, without penetrating it; wherein the water is “sucked” through the pipe by a centrifugal pump located outside the tank; and        an extremely heavy pumping structure placed directly onto the geomembrane liner on the tank floor.        
For example a common pump solution is to use suction piping through the wall or floor of the tank, feeding centrifugal pumps. This system is undesirable because it involves cutting a hole in the leak-proof layer, and then re-sealing it. Also, the pumps are less robust than submersible pumps, and there is often no redundancy in case of pump failure which puts the water transfer at risk (and therefore the well completion).
Another system currently available uses a single 10″ suction pipe that extends up alongside the wall of the tank and feeds a centrifugal pump(s). This system provides little redundancy and is risky if a pump or power failure occurs. Also, output from centrifugal pump may not be consistent depending on the depth of water in the tank.
Yet another pump solution uses submersible pumps and an extremely heavy stair system. This system includes built in stairs that run over the wall of the tank. In this solution a number of submersible pumps are used that cavitate when in use as the pump intakes compete for available water. The bulk of the weight of the stairs is placed on the liner at the floor of the tank. The problem with this is that the pumps put a great deal of stress and pressure on the liner. The system is also extremely large, and not portable, requiring special trailers for highway transportation and large cranes for positioning. The size also poses a safety risk for workers potentially falling into the tank.
The problem with the prior art methods is that the geomembrane liner integrity is compromised, and the tank is therefore at risk of leaking. Also, the pump systems used often do not meet the flow rates required, as well as the total dynamic head (TDH) required (the TDH can be translated into required pump pressures).
In order to reach the required TDH of the system, previous methods have used a booster pump to increase the pumping pressure. These booster pumps are typically centrifugal pumps (diesel or electric) placed outside the water storage tank.
Placing the booster pump outside the storage tank increases the risk of environmental damage in case of pump failure (a spill). In general, an exterior booster pump is fragile and susceptible to pipe stress, which may lead to material fatigue and failure.